Feeding

I mean their tummies are still tiny. 21 oz is pretty good still sometimes babies will drink more and some less

3-4 ounces roughly every 3-4 hours is the appropriate amount for a 5 week old baby. If she’s taking less follow her lead, don’t force feed her. It’s only a concern if she’s underweight

The important thing is wet and dirty diapers for her age, and that she's gaining weight. I will say from a mom of a chewing newborn, do have them checked for a tongue tie just in case

It's ok that they don't have the same amount at every bottle throughout the day. Do you eat the same amount for every meal every day?

The thing to pay attention to is wet nappies, and dirty nappies to an extent but there can be several days between poos without concern